Engraving stylus



April 24, 1956 J. A. BOYAJEAN EINGRAVING STYLUS Filed Aug. 30, 1952 FIG.1

JNVENTOR. JOHN A. BOYAJEAN 3/ ATTORNEY United States Patent 2,743,348 ENGRAVING STYLUS John A. Bo'yajean, Huntington, N. Y., assignor to Fairchild Camera and Instrument Corporation, a corporation of-Delaware Application August 30, 1952, Serial No. 307,339 4 Claims. (Cl. 219-21) engraving image-reproducing plates-by the apparatus described and claimed in applicantswprior Patent No. 2,575,546 entitled Machine for ProducingScreened Relief Pattern Plates.

In the engraving of plates of thermally decomposable material, such as cellulose-nitrate, by a machine of the type described in the above patent,

It is an object of the present invention, therefore, to provide a new and improved engraving stylus which obviates one or more of the foregoing disadvantages of engraving styli heretofore proposed.

It is another object of the invention to provide a new and improved engraving stylus characterized by relatively free heat flow from the heating coil to the engraving tip of'the stylus.

It is a further object of the invention to provide a new and" improved engraving stylus including provisions for shielding a platebeing engraved from direct radiation from the heater coil while engraving.

In accordance with the invention, a heatable stylus for engraving a plate of thermally deformable material and designed for oscillation at a frequency of at leasta few hundred cycles per second comprises a metallic shaft having a diameter not exceeding a few tenths of an inch and having a substantially helical channel extending along its periphery substantially to the end thereof and terminating at said end in a deforming tip and an electric heating coil disposed in the channel and adapted for operation at a temperature at least of the order of 1800 F. so that heat is transferred to the stylus by radiation and conduction.

For a better understanding of the present invention, together with other and further objects thereof, reference is had to the following description taken in connection with the accompanying drawing, while its scope will be pointed out in the appendedclaims.

Fig. 1 of the drawing is a longitudinal view, partly in section, of'an engraving. stylus embodying the invention; while Fig. 2 is a similar view of a-modified ing stylus embodying coil-is in the form. of'ataper'edhelix.

Referring now toFig'. lot the drawing, there is illustrated a heatablestylus form of engravcross section, while the tip exceeding, and preferably somewhat less than, the root diameter of the shaft 10. The tip 12 is preferably conical or pyramidal having an apex angle between 60 and 90 and preferably of the order of The stylus of Fig. lalso includes means for heating the tip 12, the heating means preferably being in the form of an electric heating coil 13 disposed in the channel 11 and provided with lead conductors 14 and 15. The electric heating coil 13 is-of a material capable of operating at high temperatures so mally utilized. The coil 13 is formed of a wire having a cross-sectional area substantially-equal to that of the channel 11.

The stylus of Fig 1 further includes means for shielding a plate being engraved'from To this end, the channel 11'. terminates in a radially exsurrounding the end'of the shaft.

stock, as by milling, desired, the. portion of the shaft 11 and the baffle 16 may be enclosed in a heat insulating shield or jacket 17 surroundingthe coil 13.

With aconstruction .ofthe type described above, a sub.- stantial portion of the heat isv transferred from the coil 13 to the shaft 10 by radiation and the rest by. conduction. For this purpose, the wire should operate at a temperature in the range of 1800 F. to 1900" R, which is of a bright'cherry red" color. Radiation takes place radially outward from the surface of the wire of the coil 13 in all directions and, with the wire inserted in the channel and substantially filling the a cherry red color even to its engraving point, while in perceptibly for an appreciable distance back from the engraving point. With the enthe invention in which theheatin'g graving point of the stylus maintained at this higher temperature, the stylus is capable of forming a greater number of deformations per second and thus of imparting a higher engraving speed to a machine to which it is applied. At the same time, the end fin or bafiie 16 shields the plastic plate during engraving from direct radiation from the coil 13, particularly the end turn thereof, to prevent softening and buckling of the plate. The heat-insulating shield 17 serves to conserve the heat developed by the coil 13 and thus further improve the efficiency of the stylus.

While the parameters of the stylus of Fig. 1 may be varied in accordance with particular applications, one satisfactory design has the following specifications:

From the foregoing specifications it is seen that the diameter of the shaft does not exceed a few tenths of an inch so that it has a small inertia such that it can be readily oscillated at frequencies of a few hundred cycles per second or more required for making screened relief pattern plates, for example at 350 cycles per second specified in applicants prior Patent 2,575,546 referred to above.

In Fig. 2 is illustrated a modified form of the invention in which corresponding elements are given similar reference numerals. The essential difference in the stylus of Fig. 2 is that the channel 11 is in the form of a tapered helix and the coil 13 has a similar configuration. With this construction, the end turn of the coil 13, which is primarily effective in the transfer of heat to the tip 12, is disposed somewhat closer to the tip so that the path of heat flow by conduction through the shaft 10 is somewhat shortened. The heat-insulating shield 17 is shown as omitted from the stylus of Fig. 2, but this tha of course, be added if desired. The principles of operation of the stylus of Fig. 2 are in all respects similar to those of Fig. 1 described above.

While there have been described what are at present considered to be the preferred embodiments of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein Without departing from the invention, and it is, therefore, aimed in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What is claimed is.

1. A heatable stylus for engraving a plate of thermally deformable material and designed for oscillation at a 'frequency of at least a few hundred cycles per second and comprising: a metallic shaft having a diameter not exceeding a few tenths of an inch and having a substantially helical channel extending along its periphery substantially to one end thereof and terminating at said end in a deforming tip; and an electric heating coil disposed in said channel and adapted for operation at a temperature at least of the order of 1800 P. so that a substantial portion of the heat is transferred to the stylus by radiation, said coil being formed of a wire having a cross sectional area substantially equal to that of said channel.

2. A heatable stylus for engraving a plate of thermally deformable material and designed for oscillation at a frequency of at least a few hundred cycles per second and comprising: a metallic shaft having a diameter not exceeding a few tenths of an inch and having a substantially helical channel extending along its periphery substantially to one end thereof and terminating at said end in a tapered deforming tip, the apex angle of said tip being not substantially less than 60; and an electric heating coil disposed in said channel and adapted for operation at a temperature at least of the order of 1800 P. so that a substantial portion of the heat is transferred to the stylus by radiation.

3. A heatable stylus for engraving a plate of thermally deformable material and designed for oscillation at a frequency of at least a few hundred cycles per second and comprising: a metallic shaft having a diameter not exceeding a few tenths of an inch and having a substantially helical channel extending along its periphery substantially to one end thereof and terminating at said end in a deforming tip; an electric heating coil disposed in said channel and adapted for operation at a temperature at least of the order of 1800 P. so that a substantial portion of the heat is transferred to the stylus by radiation; and means for shielding a plate being engraved from direct radiation from said coil.

4. A heatable stylus for engraving a plate of thermally deformable material and designed for oscillation at a frequency of at least a few hundred cycles per second and comprising: a metallic shaft having a diameter not exceeding a few tenths of an inch and having a substantially helical channel extending along its periphery substantially to one end thereof and terminating at said end in a deforming tip, said channel terminating in a radially extending baflie surrounding the end of the shaft; and an electric heating coil disposed in said channel and adapted for operation at a temperature at least of the order of 1800 P. so that a substantial portion of the heat is transferred to the stylus by radiation.

References Cited in the file of this patent UNlTED STATES PATENTS 1,982,646 Dick Dec. 4, 1934 2,031,532 Goldman Feb. 18, 1936 2,357,906 Osterheld Sept. 12, 1944 2,360,264 Osterheld Oct. 10, 1944 2,474,3 l2 Halpern June 28, 1949 FOREIGN PATENTS 203,510 Great Britain Sept. 13, 1923 617,414 Germany Aug. 19, 1935 933,933 France May 5, 1943 

